A study lead by researchers from Brigham and Women's hospital (BWH) shows an association between increased concentrations of phthalates in the body and an increased risk of diabetes in women. Phthalates are endocrine disrupting chemicals that are commonly found in female personal care products such as moisturizers, nail polishes, soaps, hair sprays and perfumes. They are also used in adhesives, electronics, toys and a variety of other products. This finding is published in the July 13, 2012 online edition of Environmental Health.

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Diabetes mellitus, often simply referred to as diabetes, is a group of metabolic diseases in which a person has high blood sugar, either because the body does not produce enough insulin, or because cells do not respond to the insulin that is produced. This high blood sugar produces the classical symptoms of frequent urination, increased thirst and increased hunger.

The three main types of diabetes are:

Type 1 results from the body's failure to produce insulin, and presently requires the person to inject insulin.

Type 2 results from insulin resistance, a condition in which cells fail to use insulin properly, sometimes combined with an absolute insulin deficiency.

Gestational diabetes is when pregnant women, who have never had diabetes before, have a high blood glucose level during pregnancy.

Researchers, lead by Tamarra James-Todd, PhD, a researcher in the Division of Women's Health at BWH, analyzed urinary concentrations of phthalates in 2,350 women who participated in the National Health and Nutrition Examination Survey. They found that women with higher levels of phthalates in their urine were more likely to have diabetes. Specifically:

Women who had the highest levels of the chemicals mono-benzyl phthalate and mono-isobutyl phthalate had almost twice the risk of diabetes compared to women with the lowest levels of those chemicals.

Women with higher than median levels of the chemical mono-(3-carboxypropyl) phthalate had approximately a 60 percent increased risk of diabetes.

Women with moderately high levels of the chemicals mono-n-butyl phthalate and di-2-ethylhexyl phthalate had approximately a 70 percent increased risk of diabetes.

The study population consisted of a representative sample of American women and was controlled for socio-demographic, dietary and behavioral factors. However, the women self-reported their diabetes and researchers caution against reading too much into the study due to the possibility of reverse causation.

"This is an important first step in exploring the connection between phthalates and diabetes," said Dr. James-Todd.

People are commonly exposed to phthalates, and most Americans tested by the Centers for Disease Control and Prevention have metabolites of multiple phthalates in their urine. Endocrine disruptors are chemicals that interfere with endocrine (or hormone system) in animals, including humans. These disruptions can cause cancerous tumors, birth defects, and other developmental disorders. In studies of rodents exposed to certain phthalates, high doses have been shown to change hormone levels and cause birth defects.